From the basics of router hardware to configuring and troubleshooting BGP, let’s test your knowledge of Cisco certification exam topics!
You’ve just run the show interface ethernet0 command and you see the interface is “administratively down”. What causes that?
Answer: The interface is shut down. Just run no shutdown on the interface to open it. When the interface shows as simply “down”, that indicates an issue with the cable, or more likely the interface on the other end of the connection is not open.
The interface can be physically up and logically down, and that’s indicated by the output of show interface displaying the message “serialx is up, line protocol is down”. If the line protocol is down, that indicates the lack of a keep alive or a timing issue, such as a missing clockrate command.
What’s the broadcast address for a frame?
Answer: The all-Fs MAC address, ff-ff-ff-ff-ff-ff (or FF-FF-FF-FF-FF-FF, as there’s no difference between upper and lower case in hexadecimal numbering.)
CCNP Certification / BSCI Exam:
What port number does BGP use to create and maintain adjacencies?
Answer: TCP port 179. Don’t block that one with an ACL! 🙂
CCNP Certification / BCMSN Exam:
What’s the maximum number of physical channels that can be placed into an Etherchannel?
CCNP Certification / ONT Exam:
What’s the full command for doubling the capacity of the default queue when Priority Queuing is in use?
Answer: Assuming we’re using list 1:
priority-list 1 queue-limit 20 40 120 80.
From left to right, we’re defining the limit for the high, medium, normal, and low-priority queues. The default queue is the normal-priority queue, and the default capacity for that queue is 60 packets. Even though we’re only changing one value, the IOS will make us list a value for all four queues.
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